The invention pertains to the field of cleansers for skin, and most particularly to skin cleansers that may be used on sensitive, damaged, diseased, or irritated skin.
Cleansing products represent one of the major risk factors for occupational dermatitis, particularly hand dermatitis. Chronic irritant contact dermatitis is due in many cases to repeated exposure to weak irritants, such as present in many skin cleansers. Also, certain endogenous skin diseases, such as atopic dermatitis, are exacerbated by exposure to irritants found in these cleansing products. Additionally, many individuals who have sensitive skin, even without having dermatitis, experience symptoms of irritation, such as redness, stinging, tingling, burning and itching, when using topical cleansing products on intact skin.
The mildness (lack of tendency to cause irritation) of a cleansing product is related to the formulation of the particular detergent or detergents and their concentration in the cleansing product. Also, the risk of chronic irritant dermatitis or exacerbation of endogenous dermatitis increases with increased frequency of washing. This is especially a problem in occupations that require frequent hand washing, such as in workers in the medical and food service fields.
CETAPHIL(copyright) Cleanser (Galderma Laboratories, Ft. Worth, Tex.) is recognized as the leading mild skin cleanser and is frequently recommended by physicians for use by patients with atopic dermatitis and hand dermatitis. Even though this product is recognized as being mild, tests have shown that its use results in significant irritation to human skin when evaluated in a patch test. Chronic use of CETAPHIL(copyright) or other cleansing products made for skin can perpetuate or worsen a dermatitis, particularly in individuals with sensitive skin.
Therefore, a significant need exists for a milder skin cleanser for individuals with sensitive skin, atopic dermatitis, or latent, incipient or frank hand dermatitis. In addition to being mild, such a hand cleanser should be effective as a cleanser and should moisturize.
The present invention is a major improvement in mild skin cleansers and in methods of cleansing skin. Although useful in individuals with normal skin, the invention is most useful in those individuals with sensitive skin who are vulnerable to developing skin disorders and those individuals who are currently suffering from such disorders.
In one embodiment, the invention is a composition for cleansing skin, especially for diseased or sensitive skin. The composition is most useful for cleaning the hands, but may also be used to clean the skin on any other part of the body. The composition of the invention is demonstrably less irritating than CETAPHIL(copyright) Cleanser in a comparative repeat insult patch test. The composition is stable, cosmetically elegant, well tolerated by users, and cleanses effectively while moisturizing the skin. Compositions of this invention may be safely used for frequent cleansings such as hand washings required of food workers and medical personnel. The composition may also be used to prevent or to treat or manage dermatitis, especially hand dermatitis.
In another embodiment, the invention is a method for cleaning skin, such as the skin of the hands. According to this embodiment, a formulation containing the composition of the invention is applied to the skin. The formulation is then removed from the skin, either with or without water.
In another embodiment, the invention is a method for prevention of dermatitis in individuals susceptible to developing dermatitis, especially of the hands. According to this embodiment, the invention comprises cleansing the skin with a formulation containing the composition of the invention by applying the formulation to the skin and then removing it from the skin.
In another embodiment, the invention is a method for treatment or management of dermatitis, especially hand dermatitis. According to this embodiment, an individual suffering from this condition cleanses his or her skin with a formulation containing the composition of the invention.
In another embodiment, the invention is a method for making a moisturizing skin cleanser. According to this embodiment, the method includes combining one or more non-ionic surfactants with a glyceryl monoester. Preferably, one or more saturated fatty alcohols is also combined with the surfactant and the glyceryl monoester.
The composition of the invention is useful as a component of a formulation, or as the entire formulation, that is useful as a skin cleanser, particularly for the hands. The skin cleanser is especially useful for preventing dermatitis in susceptible individuals and in managing and treating individuals suffering from dermatitis, such as atopic dermatitis or hand dermatitis. The cleanser of the invention may be used with or without water during the cleansing process. The water may be used to increase the lather of the cleanser or to rinse the cleanser from the skin of the user. Cleansing without water may be accomplished by massaging the cleanser onto the skin to be cleaned and then wiping any soil and excess cleanser off the skin with a cloth or paper towel or facial tissue.
According to the invention, the composition of the invention contains one or more non-ionic surfactants. Examples of suitable non-ionic surfactants include poloxamers and steareths.
Poloxamers are also known as polyoxyethylene polyoxypropylene block polymers. They are sold under the trade name PLURONIC(trademark) by BASF of Washington, N.J., which markets several grades of PLURONIC(trademark). A preferred poloxamer for the composition of the invention is poloxamer 123, as described in the National Formulary. The BASF name for this poloxamer is PLURONIC L43.
One company that makes steareths is ICI America of Wilmington, Del., where they are sold under the trade name BRIJ(trademark). One preferred steareth for the composition of the invention is BRIJ 72, which is also known as steareth-2. Other names for steareth-2 are PEG-2 Stearyl Ether, Polyoxyethylene (2) Stearyl Ether, and Polyethylene Glycol 100 Stearyl Ether. Other preferred steareths for the composition of the invention are BRIJ 78 and 721, which are also known as steareth-20 and 21, respectively.
Suitable total concentrations of non-ionic surfactant for the composition and formulation of the invention are from about 0.5% to about 10% by weight for poloxamers and/or steareths. A preferred range is from about 1% to about 5%, and a most preferred range from about 1.25% to about 2.5%.
The composition of the invention further contains one or more glyceryl monoesters of a fatty acid, also known as fatty acid monoglycerides. The terms xe2x80x9cglyceryl monoesterxe2x80x9d and xe2x80x9cmonoglyceridexe2x80x9d are used synonymously throughout this specification to in reference to fatty acid esters. It has been discovered that such glyceryl monoesters in accordance with the invention provide unexpected benefits to the compositions of the invention, including physical stabilization and reproducibility of pharmaceutical attributes. The glyceryl monoesters have also unexpectedly been found to contribute to the moisturizing properties and to the mildness of the compositions of the invention. Preferably, the monoester content or purity, also known as the monoglyceride content or purity, of the glyceryl monoester is at least about 50%, although it may be lower if desired, such as between 35% and 50%. Preferably, the fatty acid component of the glyceryl monoester is of fatty acids having a chain length of between C8 to C22, which fatty acids are preferably substantially or entirely saturated.
Suitable total concentrations of glyceryl monoester for the composition and formulation of the invention are from about 0.1% to about 5% by weight. A preferred concentration of glyceryl monoester is from about 0.5% to 2%. The most preferred concentration is about 1%.
A preferred glyceryl monoester is glyceryl monolaurate, sold for example under the trade name IMWITOR 312 (Salol Co., Houston, Tex.). The characteristic monoglyceride purity is about 90% or more. Other technical names for glyceryl monolaurate include glyceryl laurate, 1-monolaurin, monolaurin, glycerin 1-monolaurate, glycerol 1-monolaurate and lauric acid 1-monoglyceride. Another preferred glyceryl monoester is glyceryl monostearate, sold for example under the trade names EMEREST 2400 (Henkel, Hoboken, N.J.) and IMWITOR 191 or IMWITOR 900 (Salol Co., Houston, Tex.). The characteristic monoglyceride purity of IMWITOR 191 is about 90% or more for example, and the purity of IMWITOR 900 is characteristically about 42% to about 50%. Glyceryl monostearate is also known by the following technical names: glyceryl stearate, monostearin, glycerol 1-stearate, and stearic acid 1-monoglyceride. Some commercial formulations of glyceryl monoesters are blended with emulsifiers to make the mixture self-emulsifying. Such materials, such as ARLACEL 165 (ICI Americas, Inc.) are neither required nor preferred for the present invention.
An optional component of the composition of the invention is one or more saturated fatty It alcohols. Preferred saturated fatty alcohols include cetyl and stearyl alcohols. Saturated fatty alcohols can be obtained from various suppliers known to one skilled in the art. The NF grade is preferred for the saturated fatty alcohols. If present, the total concentration of the saturated fatty alcohols in the composition may be from about 0.25% to about 5% by weight. Higher or lower concentrations of saturated fatty alcohols may be used if desired. The preferred amount is about 0.5% to about 4%, and the most preferred amount is from about 1.5% to about 3.5%.
The composition of the invention may further include one or more humectants. Preferred humectants include glycerin and sorbitol. The humectants can be obtained from various suppliers known to one skilled in the art. The USP grade is preferred for glycerin and for sorbitol. If present, the total concentration of the humectant or humectants in the composition may be from about 0.5% to about 15% by weight. Higher or lower concentrations of humectant may be used if desired. The preferred concentration range is from about 2.5% to about 10%, and the most preferred range of concentration is from about 3% to about 5%.
Other optional ingredients may be included in the invention to provide additional properties. For example, the composition may include a preservative to prevent spoilage. Fragrances and odor maskers may also be used. However, fragrances and odor maskers are not preferred because of the potential for irritation and allergic reactions.
Preferably, although not necessarily, the composition of the invention is substantially free of ethylene glycol fatty acid ester. Preferably, although not necessarily, the composition of the invention is substantially free of fatty acid soap.
In preferred embodiments, the composition and formulation of the invention are liquids. Preferably, the invention is a mild, low foaming, aqueous fluid cleanser that is pourable from a bottle or dispensable by a pump or squeeze bottle. Preferably, the liquid cleanser of the invention has a viscosity less than about 17000 centipoise, and most preferably between 7000 and 17000 centipoise. Other physical forms of the invention are also conceived, like a solid or semisolid, such as resembling a bar of soap.
The composition of the invention may be made by combining the ingredients in an aqueous medium and mixing to distribute all the ingredients substantially evenly throughout the aqueous medium. Preferably, the water and the other ingredients are heated to about 70xc2x0 C. or higher. Preferred methods of making the composition of the invention are described below.